1. Field of the Invention
The present invention relates to a printing system, printing apparatus, and printing control method for printing out print data sent from, e.g., a host computer.
2. Related Background Art
Conventionally, a page printer dedicated to image output is known, and is called a host-based printer.
In case of the host-based printer, a host computer compresses mapped image data for one page and sends the compressed data to a controller unit of the printer. The controller unit expands the received compressed data, converts the expanded data into a video signal, and outputs the video signal to an engine unit in synchronism with the paper discharge timing of the engine unit. In this way, printing on a paper sheet for one page is done.
In such printer, conversion of compressed image data into a video signal and video signal output to the engine unit are done by a hardware circuit. Ultimately, the controller unit does not require any CPU, and a very low-cost page printer can be provided.
However, the host computer that uses the conventional host-based printer must perform character mapping, figure drawing, image pasting, and the like. That is, after the host computer maps all print data as image data, it compresses the mapped image data and transfers the compressed data to the printer. For this reason, the volume of data to be transferred from the host computer to the printer becomes large. Also, the host computer must temporarily process characters and elements other than characters, e.g., must perform table ruled line drawing, figure drawing, image pasting, and the like, map them as image data, compress the mapped image data, and transfer the compressed data to the printer. For this reason, the transfer data volume becomes large, and the long processing time on the host computer extends the total processing time.